Falkirk High School has been forced to close for a week following a surge in coronavirus cases.
The pupils will now move to remote learning from Friday until June 11.
In a letter to parents and carers on Thursday, the health board said there had been a “recent rise” in the number of staff and pupils testing positive for the deadly virus.
The decision to close the secondary school was made following detailed discussions between Falkirk Council, NHS Forth Valley, Public Health Scotland and the Scottish Government.
In the letter signed by Dr Henry A. Prempeh, consultant in public health medicine, and David Mackay, head of education, it said the move was part of a series of actions to try to prevent the new Delta variant from spreading more widely, resulting in the need for more prolonged or additional control measures.
All staff, pupils and their families are now being urged to undergo PCR testing to help identify any further cases, even if they don’t have Covid symptoms.
A mobile testing centre will be located in the school’s main car park from 10am until 5pm from Friday through to Tuesday, June 8.
The letter said: “No appointment is necessary, so please just turn up although all pupils must be accompanied by an adult.
“If the testing centre is busy please return when it’s quieter or book an appointment at one of the alternative locations.”
Additional testing facilities are available at Abbotsford House, Howgate Shopping Centre and Slamannan Community Centre.
Tests should be booked online or by calling 0300 303 2713.
There will be no hub for vulnerable youngsters or for the children of key workers, but school staff will be in touch with “relevant families and advise of further support available”.
The letter added: “All of the organisations involved are fully aware of the impact this decision may have, especially on those senior pupils who are required to complete assessments as part of the SQA certification process for this year.
“School staff will be in contact with senior pupils who require to complete assessments and arrangements will be communicated to those affected directly.
“Thank you for your continued support.”